Unilateral leg swelling, pain, or erythema
Recommended: Lower extremity venous Doppler Ultrasound is the preferred imaging study for unilateral leg swelling, pain, or erythema. First-line for evaluating asymmetric leg findings.
Recommended study
Lower extremity venous Doppler Ultrasound
First-line for evaluating asymmetric leg findings. Bilateral if both legs symptomatic. Repeat in 5-7 days if initial study negative but clinical suspicion remains high.
If the default doesn't apply
US negative + high clinical suspicion or symptoms persist
US
Repeat lower extremity Doppler in 5–7 days
No contrast
Bilateral leg swelling concern (May-Thurner, IVC)
CT
CT or MR Venography Pelvis / IVC
IV contrast
Concurrent PE concern
CT
CT Pulmonary Angiogram
IV contrast
Watch-outs
Iliofemoral or extensive proximal DVT
Consider catheter-directed thrombolysis to reduce post-thrombotic syndrome.
Wells score for DVT
Stratify before imaging — low-probability patients with negative d-dimer can avoid imaging.
Pearls
- Acute DVT: non-compressible vein, expanded vessel, hypoechoic thrombus.
- Chronic DVT: partially recanalized, echogenic, residual webs — distinguish from new clot.
- Calf-only (distal) DVT is often managed without anticoagulation; proximal DVT always anticoagulated.